Porphyry Island is the last island in a chain stretching southwest
from the Black Bay Peninsula. It is generally flat to rolling with
little relief and the rugged shoreline offers little shelter. The
rocks of the peninsula and the island are of Late Precambrian age
and consist of more than 300 distinctive lava flows. These ancient
volcanic flows are typically grey-green basalt intermixed with minor
amounts of sedimentary rocks. Geologists call these rocks the Osler
Group. The island and nature reserve take their name from the characteristic
quartz and feldspar crystals, or porphyries found in the
The nature reserve is on the southern margin of the boreal forest.
Its interior supports a mixed forest dominated by white birch in
the south and balsam fir in the north. Wetlands with concentrations
of black spruce are also found here. Lichens are commonly seen draping
mature trees and as barrens intermixed with hardy flowering plants
along rocky shorelines. The rocky shores also support arctic species,
like encrusted saxifrage, insectivorous butterwort and the sedge.
Of greater interest is the presence of devil's club in the forest.
Populations of this thorny shrub here, and on adjacent islands,
are the only known occurrences east of the Rocky Mountains.
Park Facilities and Activities
This nature reserve is managed to protect its significant biological
and geological values. There are no visitor facilities and the islands
remote location makes visitation difficult. The unauthorized collection
of rare plants and other natural objects from the nature reserve
is prohibited. Anyone wishing to conduct scientific research must
obtain an approved research application.
Location: The southern end of the Black Bay Peninsula,
in Lake Superior, east of Sleeping Giant Provincial Park.
For more information:
Northwest Zone Manager
435 James Street South
Thunder Bay, Ontario